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Background and Purpose: At 12 months in the phase 2 TOPAZ study, treatment with apitegromab was associated with both an improved motor function in patients with Type 2 or 3 spinal muscular atrophy (SMA) and with a favorable safety profile. This manuscript reports the extended efficacy and safety in the nonambulatory group of the TOPAZ study at 36 months., Methods: Patients who completed the primary study (NCT03921528) could enroll in an open-label extension, during which patients received apitegromab 20 mg/kg by intravenous infusion every 4 weeks. Patients were assessed periodically via the Hammersmith Functional Motor Scale-Expanded (HFMSE), Revised Upper Limb Module (RULM), World Health Organization (WHO) motor development milestones, Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) Daily Activities and Mobility domains, and Patient-Reported Outcomes Measurement Information System (PROMIS) Fatigue questionnaire., Results: Of the 58 patients enrolled in TOPAZ, 35 were nonambulatory (mean age 7.3 years). The mean change at 36 months in HFMSE score from baseline was +4.0 (standard deviation [SD]: 7.54), and + 2.4 (3.24) for RULM score (excluding n  = 7 after scoliosis surgery). Caregiver-reported outcomes (PEDI-CAT and PROMIS Fatigue) showed improvements from baseline over 36 months. In addition, most patients (28/32) improved or maintained WHO motor milestones achieved at baseline. The most frequently reported treatment-emergent adverse events were pyrexia (48.6%), nasopharyngitis (45.7%), COVID-19 infection (40.0%), vomiting (40.0%), and upper respiratory tract infection (31.4%)., Conclusion: The benefit of apitegromab treatment observed at 12 months was sustained at 36 months with no new safety findings., Competing Interests: TC is the lead principal investigator of the TOPAZ study; and a consultant and/or advisory board member for AveXis/Novartis, Biogen, Pfizer, and Roche/Genentech. JD has received consulting fees from Biogen, Cytokinetics, Ionis Pharmaceuticals, NGT, Pfizer, Roche, and Sarepta Therapeutics; license fees or royalty payments from Athena Diagnostics; and research funding from Biogen, Cytokinetics, NGT, Roche, Sanofi-Genzyme, and Sarepta Therapeutics. DV reports grants from Biogen during the conduct of the study, Department of Defense, Hope for Children Research Foundation, National Institutes of Health, and Spinal Muscular Atrophy Foundation; and personal fees from AveXis, Biogen, Cytokinetics, Ionis Pharmaceuticals, Inc., Roche, and Sarepta. JK was site principal investigator for clinical trials sponsored by Biohaven, Fibrogen, Novartis Gene Therapies, Inc., and Scholar Rock. EM is a primary investigator and advisory board/consultant for Biogen, Epirium, Novartis, Roche, and Scholar Rock; and has grants to the institution from Biogen, Novartis, and Roche. AN receives honoraria for counseling and invited talks from F. Hoffmann-La Roche, Ltd., Biogen, Novartis, Pfizer, PTC Therapeutics, Sarepta Therapeutics, Inc., Scholar Rock, and UCB Pharma. AP is an advisory board member and consultant for Scholar Rock and has served as an ad hoc scientific advisory board member for AveXis/Novartis Gene Therapies and Roche/Genentech. ESM has received consulting fees from Biogen, Novartis, Roche, and Scholar Rock. TD is an advisory board member for Biogen, CureSMA, Novartis, Roche, and Scholar Rock; and a consultant for Astellas, Avidity, Biohaven, Dyne, Genentech, Novartis, Roche, and Sarepta Therapeutics. GS, JM, DY, and LL are all full-time employees of Scholar Rock. SB was a full-time employee of Scholar Rock at the time of the study. BD has served as an ad hoc scientific advisory board member for AveXis/Novartis Gene Therapies, Biogen, Pfizer, Roche/Genentech, Sarepta Therapeutics, and Vertex; steering committee chair for Roche FIREFISH and MANATEE studies and DSMB member for Amicus Inc. and Lexeo Therapeutics; he has no financial interests in these companies. He has received research support from the National Institutes of Health/National Institute of Neurological Disorders and Stroke, the Slaney Family Fund for SMA, the Spinal Muscular Atrophy Foundation, CureSMA, and Working on Walking Fund; received grants from Ionis Pharmaceuticals, Inc. for the ENDEAR, CHERISH, and CS2/CS12 studies; from Biogen for CS11; and from AveXis, Fibrogen, Novartis (AveXis), PTC Therapeutics, Roche, Sarepta Pharmaceuticals, and Scholar Rock; and has received royalties for books and online publications from Elsevier and UpToDate, Inc. The authors declare that this study received funding from Scholar Rock, Inc. In collaboration with the academic authors, the funder was involved in the study design, data collection and analysis, interpretation of data, decision to publish, and the preparation of the manuscript. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Crawford, Day, De Vivo, Krueger, Mercuri, Nascimento, Pasternak, Mazzone, Duong, Song, Marantz, Baver, Yu, Liu and Darras.)

Background and Objectives: Nusinersen has shown significant functional motor benefit in the milder types of spinal muscular atrophy (SMA). Less is known on the respiratory outcomes in patients with nusinersen-treated SMA. The aim of this study was to describe changes in respiratory function in pediatric patients with SMA type 2 and 3 on regular treatment with nusinersen within the iSMAc international cohort and to compare their trajectory with the natural history (NH) data published by the consortium in 2020., Methods: This is a 5-year retrospective observational study of pediatric SMA type 2 and nonambulant type 3 (age ≤18 years) treated with nusinersen. The primary objective was to compare the slopes of decline in forced vital capacity % predicted (FVC% pred.), FVC, and age when FVC dropped below 60% between the treated patients and a control group from the natural history cohort. Data on peak cough flow and the use of noninvasive ventilation (NIV) and cough assist were collected., Results: Data were available for 69 treated patients, 53 were SMA type 2 and 16 type 3. The mean (SD) age at first injection was 8.5 (3.2) and 9.7 (3.7) years, respectively. The median (interquartile range) treatment duration was 1 (0.7; 1.9) and 1.2 (0.9; 1.9) years, respectively. At the time of the first nusinersen injection, 24 of 52 (46%) patients with SMA type 2 and 2 of 16 (13%) patients with SMA type 3 were on NIV. Forty-three of 53 (81%) and 4 of 16 (25%) patients used cough device. FVC% pred. in treated patients with SMA type 2 declined annually by 2.3% vs 3.9% in NH ( p = 0.08) and in treated patients with type 3 by 2.6% vs 3.4% NH ( p = 0.59). Patients treated reached FVC <60% later than untreated (12.1 vs 10 years, p = 0.05). A higher percentage of treated vs untreated patients maintained FVC% pred. equal/above their baseline after 12 (65% vs 36%) and 24 (50% vs 24%) months, respectively. NIV use among treated did not significantly change throughout 1-year follow-up., Discussion: This study included the largest real-world cohort of pediatric patients with milder SMA types. The results suggest a positive role of nusinersen in delaying the respiratory decline in patients treated longer than 1 year when compared with natural history. Larger cohorts and longer observation are planned., Classification of Evidence: This study provided Class III evidence that nusinersen slows progression for patients with SMA types 2 and 3 compared with a natural history cohort., Competing Interests: F. Trucco reports participation to Scientific Advisory Boards for Roche UK and teaching initiatives for Biogen, Avexis, Roche, and BREAS. D. Ridout, I. Hughes, Z. Zolkipli-Cunningham, and M. Main report no disclosures. M. Scoto reports participation in Scientific Advisory Boards and teaching initiatives for Avexis, Biogen, and Roche. She is involved as an investigator in clinical trials from Avexis, Biogen, and Roche. In addition, she is the co-principal investigator of the SMA REACH UK clinical network, partially funded by Biogen and Roche. F. Muntoni reports participation in Scientific Advisory Boards and teaching initiatives for Biogen, Roche, and Novartis. He is member of the Rare Disease Scientific Advisory Board for Pfizer. He is involved as an investigator in clinical trials from Novartis, Biogen, and Roche. In addition, he is the principal investigator of the SMA REACH UK clinical network, partially funded by Biogen and Roche. E. Mercuri reports participation in Scientific Advisory Boards and teaching initiatives for Biogen, Roche, Scholar Rock, and Novartis. He is involved as an investigator in clinical trials from Novartis, Biogen, Scholar Rock, and Roche. In addition, he is the principal investigator of the Italian registry participating in iSMAc, partially funded by Biogen, Roche, and Novartis. R. Finkel reports participation in Medical and Scientific Advisory Boards on SMA topics with Novartis, Biogen, Ionis, Roche, Cure SMA, SMA Europe, SMA REACH UK, SMA Foundation, and MDA. Finkel participates as an investigator in SMA-related clinical trials sponsored or supported by Novartis, Biogen, Ionis, Roche, and Scholar Rock. Dr. D. De Vivo reports participation as a consultant in Medical and Scientific Advisory Boards and as an investigator with Novartis, Biogen, Ionis, Roche, PTC, Santhera, Scholar Rock, Sanofi, GliaPharm, Fulcrum Therapeutics, Sarepta, NS Pharma, SMA Foundation, Cure SMA, DoD, NIH, Glut1 Deficiency Foundation, and Hope for Children Research Foundation. B. Darras has served as an ad hoc Scientific Advisory Board member for Novartis, Biogen, Cytokinetics, Vertex, Genentech, Roche, and Sarepta; Steering Committee chair for Roche; and Data Safety Monitoring Board member for Amicus Inc. He has no financial interests in these companies. He has received research support from the NIH/National Institute of Neurological Disorders and Stroke, the Slaney Family Fund for SMA, the Spinal Muscular Atrophy Foundation, CureSMA, and Working on Walking Fund and has received grants from Ionis Pharmaceuticals, Inc, for the ENDEAR, CHERISH, CS2/CS12 studies; from Biogen for CS11; and from Cytokinetics, Sarepta Pharmaceuticals, PTC Therapeutics, Fibrogen, and Summit. O. Mayer reports participation in Advisory Boards for Roche, Biogen, and PTC Therapeutics. He is participating in SMA REACH and iSMAC, partially funded by Biogen. C. Bruno reports participation in Scientific Advisory Boards on SMA topics with Novartis, Biogen, and Roche and participates as a principal investigator in SMA-related clinical trials sponsored by Novartis, Biogen, Ionis, and Roche. S. Messina reports participation in Scientific Advisory Boards and teaching initiatives for Novartis, Biogen, and Roche. She is involved as an investigator in clinical trials from Novartis, Biogen, Scholar Rock, and Roche. M. Pane reports participation in Scientific Advisory Boards and teaching initiatives for Novartis and Biogen. V.A. Sansone provides intellectual support in Advisory Boards and teaching activities for Biogen, Santhera, Sarepta, PTC, Dyne, Triplet, and Novartis. A. D'Amico reports participation in Scientific Advisory Board for Novartis, Roche, and Novartis and teaching initiatives for Biogen. She is also involved as an investigator in clinical trials from Novartis, Biogen, and Roche. In addition, she is an investigator of the Italian registry participating in iSMAc, partially funded by Biogen. E.S. Bertini reports participation in Scientific Advisory Boards for Novartis, Roche, Novartis, and PTC and teaching initiatives for Biogen. He is also involved as an investigator in clinical trials from Novartis, Biogen, Roche, and Novartis. In addition, he is an investigator of the Italian registry participating in iSMAc, partially funded by Biogen. C. Marini-Bettolo reports participation in Scientific Advisory Boards and teaching initiatives for Novartis, Biogen, and Roche. She is involved as an investigator in clinical trials from Novartis. In addition, she is principal investigator for the UK SMA patient registry funded by SMA UK. A. Childs reports participation in Advisory Boards for Novartis, Roche, Biogen, Santhera, and PTC Therapeutics. She is principal investigator for clinical trials supported by Sarepta, Santhera, and PTC Therapeutics. She is participating in SMA REACH and iSMAC, partially funded by Biogen. M. Ong reports participation in Advisory Boards or received consultation fees for Novartis, Roche, Biogen, and CSL Behring. She is participating in SMA REACH and iSMAC, partially funded by Biogen. Dr. A. Mayhew reports participation in Scientific Advisory Boards and teaching initiatives for Biogen and Roche. She is involved as an evaluator at site and acts as an independent consultant to train evaluators in clinical trials from Novartis, Biogen, and Roche. In addition, she is the principal investigator at Newcastle for the SMA REACH UK clinical network, partially funded by Biogen and by SMA UK. J. Montes reports participation as a consultant and on Scientific Advisory Boards for Biogen, Ionis, Roche, and Scholar Rock. G. Coratti reports consultant activities for Novartis, Biogen, Roche, Biologix, and Genesis Pharma. She is involved as a clinical evaluator in clinical trials from Novartis, Biogen, Scholar Rock, and Roche. R. De Sanctis reports consultant activities for Biogen and Roche. He is involved as a clinical evaluator in clinical trials from Novartis, Biogen, Scholar Rock, and Roche. L. Servais reports consultancy/board attendance/lectures for Novartis, Biogen, Roche, Scholar Rock, and BioHaven. A. Majumdar reports participation in Advisory Boards for Novartis, Roche, Biogen, Santhera, and PTC Therapeutics. He is principal investigator for clinical trials supported by Wave Therapeutics. He is participating in SMA REACH and iSMAC, partially funded by Biogen. D. Parasuraman reports participation in Advisory Boards for Roche, Biogen, Sarepta and has had support from PTC Therapeutics. He is principal investigator for clinical trials supported by Roche. He is participating in SMA REACH and iSMAC, partially funded by Biogen. V. Gowda reports participation in Advisory Boards or received consultation fees for Novartis, Roche, Biogen, PTC therapeutics, Wave Life Sciences, Pfizer, and Sarepta Therapeutics. She is participating in SMA REACH and iSMAC, partially funded by Biogen. FT, CB, EB, AD, EM, and MP are members of the ERN NMD (European Reference Networks). Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/cp., (© 2024 American Academy of Neurology.)

Background: The natural history of spinal muscular atrophy (SMA) is well understood, with progressive muscle weakness resulting in declines in function. The development of contractures is common and negatively impacts function. Clinically, joint hypermobility (JH) is observed but is poorly described, and its relationship with function is unknown. Methods : Lower-limb ROM (range of motion) assessments of extension and flexion at the hip, knee, and ankle were performed. ROMs exceeding the published norms were included in the analysis. The functional assessments performed included the six-minute walk test (6 MWT) and the Hammersmith Functional Motor Scale-Expanded (HFMSE). Results: Of the 143 participants, 86% ( n = 123) had at least one ROM measure that was hypermobile, and 22% ( n = 32) had three or more. The HFMSE scores were inversely correlated with hip extension JH (r = -0.60, p = 0.21; n = 6) and positively correlated with knee flexion JH (r = 0.24, p = 0.02, n = 89). There was a moderate, inverse relationship between the 6 MWT distance and ankle plantar flexion JH (r = -0.73, p = 0.002; n = 15). Conclusions: JH was identified in nearly all participants in at least one joint in this study. Hip extension, knee flexion and ankle plantar flexion JH was associated with function. A further understanding of the trajectory of lower-limb joint ROM is needed to improve future rehabilitation strategies.

Background and Objectives: Currently approved therapies for spinal muscular atrophy (SMA) reverse the degenerative course, leading to better functional outcome, but they do not address the impairment arising from preexisting neurodegeneration. Apitegromab, an investigational, fully human monoclonal antibody, inhibits activation of myostatin (a negative regulator of skeletal muscle growth), thereby preserving muscle mass. The phase 2 TOPAZ trial assessed the safety and efficacy of apitegromab in individuals with later-onset type 2 and type 3 SMA., Methods: In this study, designed to investigate potential meaningful combinations of eligibility and treatment regimen for future studies, participants aged 2-21 years received IV apitegromab infusions every 4 weeks for 12 months in 1 of 3 cohorts. Cohort 1 stratified ambulatory participants aged 5-21 years into 2 arms (apitegromab 20 mg/kg alone or in combination with nusinersen); cohort 2 evaluated apitegromab 20 mg/kg combined with nusinersen in nonambulatory participants aged 5-21 years; and cohort 3 blindly evaluated 2 randomized apitegromab doses (2 and 20 mg/kg) combined with nusinersen in younger participants ≥2 years of age. The primary efficacy measure was mean change from baseline using the Hammersmith Functional Motor Scale version appropriate for each cohort. Data were analyzed using a paired t test with 2-sided 5% type 1 error for the mean change from baseline for predefined cohort-specific primary efficacy end points., Results: Fifty-eight participants (mean age 9.4 years) were enrolled at 16 trial sites in the United States and Europe. Participants had been treated with nusinersen for a mean of 25.9 months before enrollment in any of the 3 trial cohorts. At month 12, the mean change from baseline in Hammersmith scale score was -0.3 points (95% CI -2.1 to 1.4) in cohort 1 (n = 23), 0.6 points (-1.4 to 2.7) in cohort 2 (n = 15), and in cohort 3 (n = 20), the mean scores were 5.3 (-1.5 to 12.2) and 7.1 (1.8 to 12.5) for the 2-mg/kg (n = 8) and 20-mg/kg (n = 9) arms, respectively. The 5 most frequently reported treatment-emergent adverse events were headache (24.1%), pyrexia (22.4%), upper respiratory tract infection (22.4%), cough (22.4%), and nasopharyngitis (20.7%). No deaths or serious adverse reactions were reported., Discussion: Apitegromab led to improved motor function in participants with later-onset types 2 and 3 SMA. These results support a randomized, placebo-controlled phase 3 trial of apitegromab in participants with SMA., Trial Registration Information: This trial is registered with ClinicalTrials.gov (NCT03921528)., Classification of Evidence: This study provides Class III evidence that apitegromab improves motor function in later-onset types 2 and 3 spinal muscular atrophy.

Background: Spinal muscular atrophy (SMA) is a neuromuscular disorder characterised by progressive motor function decline. Motor function is assessed using several functional outcome measures including the Revised Hammersmith Scale (RHS)., Objective: In this study, we present longitudinal trajectories for the RHS in an international cohort of 149 untreated paediatric SMA 2 and 3 patients (across 531 assessments collected between March 2015 and July 2019)., Methods: We contextualise these trajectories using both the Hammersmith Functional Motor Scale Expanded (HFMSE) and Revised Upper Limb Module (RULM). At baseline, this cohort included 50% females and 15% of patients had undergone spinal fusion surgery. Patient trajectories were modelled using a natural cubic spline with age, sex, and random effects for each patient., Results: RHS and HFMSE scores show similar trends over time in this cohort not receiving disease modifying therapies. The results confirm the strong correlation between the RHS and RULM previously observed in SMA types 2 and 3a. Scoliosis surgery is associated with a reduction of 3 points in the RHS, 4.5 points in the HFMSE for the SMA 2 population, and a reduction of 11.8 points in the RHS, and 13.4 points in the HFMSE for the SMA 3a populations. When comparing the RHS and RULM, there is a lower correlation in the type 3a's than the type 2 patients. In the SMA 2 population, there is no significant difference between the sexes in either the RHS or HFMSE trajectories. There is no significant difference in the RULM trajectory in the SMA 2 or 3a participants by sex., Conclusions: This study demonstrates that the RHS could be used in conjunction with other functional measures such as the RULM to holistically detect SMA disease progression. This will assist with fully understanding changes that occur with treatments, further defining trajectories and therapy outcomes.

Background: Long-term, real-world effectiveness and safety data of disease-modifying treatments for spinal muscular atrophy (SMA) are important for assessing outcomes and providing information for a larger number and broader range of SMA patients than included in clinical trials., Objective: We sought to describe patients with SMA treated with onasemnogene abeparvovec monotherapy in the real-world setting., Methods: RESTORE is a prospective, multicenter, multinational, observational registry that captures data from a variety of sources., Results: Recruitment started in September 2018. As of May 23, 2022, data were available for 168 patients treated with onasemnogene abeparvovec monotherapy. Median (IQR) age at initial SMA diagnosis was 1 (0-6) month and at onasemnogene abeparvovec infusion was 3 (1-10) months. Eighty patients (47.6%) had two and 70 (41.7%) had three copies of SMN2, and 98 (58.3%) were identified by newborn screening. Infants identified by newborn screening had a lower age at final assessment (mean age 11.5 months) and greater mean final (SD) CHOP INTEND score (57.0 [10.0] points) compared with clinically diagnosed patients (23.1 months; 52.1 [8.0] points). All patients maintained/achieved motor milestones. 48.5% (n = 81/167) experienced at least one treatment-emergent adverse event (AE), and 31/167 patients (18.6%) experienced at least one serious AE, of which 8/31 were considered treatment-related., Conclusion: These real-world outcomes support findings from the interventional trial program and demonstrate effectiveness of onasemnogene abeparvovec over a large patient population, which was consistent with initial clinical data and published 5-year follow-up data. Observed AEs were consistent with the established safety profile of onasemnogene abeparvovec.

Assessing endurance in non-ambulatory individuals with Spinal Muscular Atrophy (SMA) has been challenging due to limited evaluation tools. The Assisted 6-Minute Cycling Test (A6MCT) is an upper limb ergometer assessment used in other neurologic disorders to measure endurance. To study the performance of the A6MCT in the non-ambulatory SMA population, prospective data was collected on 38 individuals with SMA (13 sitters; 25 non-sitters), aged 5 to 74 years (mean = 30.3; SD = 14.1). The clinical measures used were A6MCT, Revised Upper Limb Module (RULM), Adapted Test of Neuromuscular Disorders (ATEND), and Egen Klassifikation Scale 2 (EK2). Perceived fatigue was assessed using the Fatigue Severity Scale (FSS), and effort was assessed using the Rate of Perceived Exertion (RPE). Data were analyzed for: (1) Feasibility, (2) Clinical discrimination, and (3) Associations between A6MCT with clinical characteristics and outcomes. Results showed the A6MCT was feasible for 95% of the tested subjects, discriminated between functional groups ( p = 0.0086), and was significantly associated with results obtained from RULM, ATEND, EK2, and Brooke ( p < 0.0001; p = 0.029; p < 0.001; p = 0.005). These findings indicate the A6MCT's potential to evaluate muscular endurance in non-ambulatory SMA individuals, complementing clinician-rated assessments. Nevertheless, further validation with a larger dataset is needed for broader application.

Disease-modifying treatments have transformed the natural history of spinal muscular atrophy (SMA), but the cellular pathways altered by SMN restoration remain undefined and biomarkers cannot yet precisely predict treatment response. We performed an exploratory cerebrospinal fluid (CSF) proteomic study in a diverse sample of SMA patients treated with nusinersen to elucidate therapeutic pathways and identify predictors of motor improvement. Proteomic analyses were performed on CSF samples collected before treatment (T0) and at 6 months (T6) using an Olink panel to quantify 1113 peptides. A supervised machine learning approach was used to identify proteins that discriminated patients who improved functionally from those who did not after 2 years of treatment. A total of 49 SMA patients were included (10 type 1, 18 type 2, and 21 type 3), ranging in age from 3 months to 65 years. Most proteins showed a decrease in CSF concentration at T6. The machine learning algorithm identified ARSB, ENTPD2, NEFL, and IFI30 as the proteins most predictive of improvement. The machine learning model was able to predict motor improvement at 2 years with 79.6% accuracy. The results highlight the potential application of CSF biomarkers to predict motor improvement following SMA treatment. Validation in larger datasets is needed.

Myotonic dystrophy type 1 is a dominantly inherited multisystemic disease caused by CTG tandem repeat expansions in the DMPK 3' untranslated region. These expanded repeats are transcribed and produce toxic CUG RNAs that sequester and inhibit activities of the MBNL family of developmental RNA processing factors. Although myotonic dystrophy is classified as a muscular dystrophy, the brain is also severely affected by an unusual cohort of symptoms, including hypersomnia, executive dysfunction, as well as early onsets of tau/MAPT pathology and cerebral atrophy. To address the molecular and cellular events that lead to these pathological outcomes, we recently generated a mouse Dmpk CTG expansion knock-in model and identified choroid plexus epithelial cells as particularly affected by the expression of toxic CUG expansion RNAs. To determine if toxic CUG RNAs perturb choroid plexus functions, alternative splicing analysis was performed on lateral and hindbrain choroid plexi from Dmpk CTG knock-in mice. Choroid plexus transcriptome-wide changes were evaluated in Mbnl2 knockout mice, a developmental-onset model of myotonic dystrophy brain dysfunction. To determine if transcriptome changes also occurred in the human disease, we obtained post-mortem choroid plexus for RNA-seq from neurologically unaffected (two females, three males; ages 50-70 years) and myotonic dystrophy type 1 (one female, three males; ages 50-70 years) donors. To test that choroid plexus transcriptome alterations resulted in altered CSF composition, we obtained CSF via lumbar puncture from patients with myotonic dystrophy type 1 (five females, five males; ages 35-55 years) and non-myotonic dystrophy patients (three females, four males; ages 26-51 years), and western blot and osmolarity analyses were used to test CSF alterations predicted by choroid plexus transcriptome analysis. We determined that CUG RNA induced toxicity was more robust in the lateral choroid plexus of Dmpk CTG knock-in mice due to comparatively higher Dmpk and lower Mbnl RNA levels. Impaired transitions to adult splicing patterns during choroid plexus development were identified in Mbnl2 knockout mice, including mis-splicing previously found in Dmpk CTG knock-in mice. Whole transcriptome analysis of myotonic dystrophy type 1 choroid plexus revealed disease-associated RNA expression and mis-splicing events. Based on these RNA changes, predicted alterations in ion homeostasis, secretory output and CSF composition were confirmed by analysis of myotonic dystrophy type 1 CSF. Our results implicate choroid plexus spliceopathy and concomitant alterations in CSF homeostasis as an unappreciated contributor to myotonic dystrophy type 1 CNS pathogenesis., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder that leads to death in early adulthood. Patients with DMD have null mutations leading to loss of functional dystrophin protein. Here we generated two DMD induced pluripotent stem cell (iPSC) lines, one with deletion of exon 51 and the other with a single nucleotide nonsense mutation (c.10171C > T). Both lines expressed high levels of pluripotency markers, had the capability of differentiating into derivatives of the three germ layers, and possessed normal karyotypes. These iPSC lines can serve as powerful tools to model DMD in vitro and as a platform for therapeutic development., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Onasemnogene abeparvovec is a recombinant adeno-associated virus serotype 9 (AAV9) vector-based gene therapy for spinal muscular atrophy (SMA). Patients with elevated titers of anti-AAV9 antibodies (AAV9-Ab) should not receive onasemnogene abeparvovec because of potential safety and efficacy implications. We conducted a retrospective study to describe the seroprevalence of anti-AAV9 binding antibodies for pediatric patients with SMA in the United States. At initial testing, 13.0% (115 of 882) of patients (mean [SD] age, 26.29 [33.66] weeks) had elevated AAV9-Ab titers. The prevalence of elevated titers decreased as age increased, with 18.2% (92 of 507) of patients ≤3 months old but only 1.1% (1 of 92) of patients ≥21 months old having elevated titers. This suggests transplacental maternal transfer of antibodies. No patterns of geographic variations in AAV9-Ab prevalence were confirmed. Elevated AAV9-Ab titers in children <6 weeks old decreased in all circumstances. Lower magnitudes of elevated titers declined more rapidly than greater magnitudes. Retesting was completed at the discretion of the treating clinician, so age at testing and time between tests varied. AAV9-Ab retesting should be considered when patients have elevated titers, and elevations at a young age are not a deterrent to eventual onasemnogene abeparvovec administration. Early disease-modifying treatment for SMA leads to optimal outcomes., Competing Interests: J.W.D. has received consulting fees from Novartis Gene Therapies, Inc., Biogen, Cytokinetics, Ionis Pharmaceuticals, Pfizer, Roche, and Sarepta Therapeutics; license fees or royalty payments from Athena Diagnostics; and research funding from Novartis Gene Therapies, Inc., Biogen, Cytokinetics, Roche, Sanofi Genzyme, and Sarepta Therapeutics. J.R.M. has received personal compensation for clinical trial consulting, serving on scientific advisory boards, and research support from Novartis Gene Therapies, Inc. A.H.M.B. is a consultant for Novartis Gene Therapies, Inc., and conducted research for Exicure, Inc. R.W.v.O. is an employee of Novartis Gene Therapies and owns Novartis stock or other equities. R.R.A. is an employee of Novartis Healthcare Private Limited, India. K.W.D. is an employee of Novartis Gene Therapies, Inc., and holds stock or other equities., (© 2023 The Author(s).)

Nusinersen has been shown to improve or stabilize motor function in individuals with spinal muscular atrophy (SMA). We evaluated baseline scoliosis severity and motor function in nusinersen-treated non-ambulatory children with later-onset SMA. Post hoc analyses were conducted on 95 children initiating nusinersen treatment in the CHERISH study or SHINE long-term extension trial. Participants were categorized by baseline Cobb angle (first nusinersen dose): ≤10°, >10° to ≤20°, and >20° to <40° (no/mild/moderate scoliosis, respectively). Outcome measures included the Hammersmith Functional Motor Score-Expanded (HFMSE) and the Revised Upper Limb Module (RULM). Regression analysis determined the relationships between baseline scoliosis severity and later motor function. For children with no, mild, and moderate scoliosis, the mean increase in HFMSE from baseline to Day 930 was 6.0, 3.9, and 0.7 points, and in RULM was 6.1, 4.6, and 2.3 points. In the linear model, a 10° increase in baseline Cobb angle was significantly associated with a -1.4 (95% CI -2.6, -0.2) point decrease in HFMSE ( p = 0.02) and a -1.2 (95% CI -2.1, -0.4) point decrease in RULM ( p = 0.006) at Day 930. Treatment with nusinersen was associated with improvements/stabilization in motor function in all groups, with greater response in those with no/mild scoliosis at baseline.

Myotonic dystrophy type 1 (DM1) is a genetic neuromuscular progressive multisystem disease that results in a broad spectrum of clinical central nervous system (CNS) involvement, including problems with memory, attention, executive functioning, and social cognition. Fractional anisotropy and mean diffusivity along-tract data calculated using diffusion tensor imaging techniques play a vital role in assessing white matter microstructural changes associated with neurodegeneration caused by DM1. In this work, a novel spectrogram-based deep learning method is proposed to characterize white matter network alterations in DM1 with the goal of building a deep learning model as neuroimaging biomarkers of DM1. The proposed method is evaluated on fractional anisotropies and mean diffusivities along-tract data calculated for 25 major white matter tracts of 46 DM1 patients and 96 unaffected controls. The evaluation data consists of a total of 7100 spectrogram images. The model achieved 91% accuracy in identifying DM1, a significant improvement compared to previous methods.Clinical relevance- Clinical care of DM1 is particularly challenging due to DM1 multisystem involvement and the disease variability. Patients with DM1 often experience neurological and psychological symptoms, such as excessive sleepiness and apathy, that greatly impact their quality of life. Some of DM1 CNS symptoms may be responsive to treatment. The goal of this research is to gain a deeper understanding of the impact of DM1 on the CNS and to develop a deep learning model that can serve as a biomarker for the disease, with the potential to be used in future clinical trials as an outcome measure.